Author: Robbins

Big Data: Innovative Technology to make TBM Tunneling more Efficient

Modern TBMs are data-driven systems, from ground investigation tools ahead of the machine to touch-screen technology in operator’s cabins, to integration with programs on the surface. Today’s TBMs, paired with cutting-edge data collection and monitoring, can efficiently bore in even the most demanding circumstances.

In this complimentary 40-minute webinar, Robbins VP of Operations Steve Chorley and Aaron McClellan, Tunnel Superintendent III for Kiewit Underground, will explore the latest and greatest innovations in technology for TBMs.  Nearly all the parameters of a TBM can be monitored today, and this data can be transmitted via radiating coaxial cables to offices on the surface or even mobile phones. Simple observations, such as cutterhead RPM and penetration rate in a given geology, can result in altered operational parameters and reduced thrust that can speed up advance and increase cutter life. All that is required is proactive analysis by management and engineers, and good communication with the TBM operator.

Watch the Recording

---

Robbins unveils Largest Hard Rock TBM in the U.S. at Mill Creek

In December 2019, the City of Dallas, Texas, USA unveiled the largest hard rock TBM ever to bore in the U.S. The 11.6 m (38.1 ft) diameter Robbins Main Beam TBM will excavate the 8 km (5 mi) Mill Creek Drainage Relief tunnel, and its size is not its only distinction. The adaptable machine will change size partway through the bore, to a more compact 9.9 m (32.5 ft).

The unique Robbins TBM will be used to dig a tunnel designed to provide 100-year flood protection for east and southeast Dallas, areas affected in recent years by severe storms. The tunnel will protect 2,200 commercial and residential properties, including Baylor Medical Center. The current drainage system in these areas was constructed 50 to 70 years ago, and only provides two to five years of flood protection. “The completion of the TBM assembly marks a major milestone in the Mill Creek Tunnel Project,” said Council Member Lee Kleinman, chair of the Transportation and Infrastructure Committee for the City of Dallas. “I’m thrilled to see this type of engineering marvel happening right here in Dallas.”

The dual-diameter aspect of the Robbins TBM will be a first-of-its-kind conversion process. The contractor, Southland/Mole Joint Venture (SMJV), will make the conversion underground about 2.8 km (1.8 mi) into the bore. The two diameters are needed as the upstream section of the tunnel is designed with a circular cross section and peak flow rate of 42 m³/sec (15,000 ft³/sec), while the downstream 2.8 km (1.8 mi) portion has a higher peak flow of 565 m³/sec (20,000 ft³/sec) and was initially designed as a horseshoe cross section. Using the TBM for the entire tunnel is less time consuming and costly. “Robbins and SMJV are working closely to create the safest and most efficient sequence for completing this conversion within the limits of the bore. The City of Dallas (Owner) and our Project Team are very excited to embark on this unique challenge,” said Nick Jencopale, Project Manager for Southland Holdings.

The Robbins TBM, named “Big Tex” with permission of the State Fair of Texas, has been designed with a specialized cutterhead including removable spacers and adjustable bucket lips to convert to a smaller diameter. The TBM will first complete its 11.6 m (38.1 ft) diameter section of the alignment, then back up about 21 m (75 ft) to a transition area for the conversion, which is expected to take six to eight weeks.

As the TBM bores, it will pass through Austin Chalk between 12 to 30 MPa (1,800 to 4,400 at depths from 31 to 46 m (100 to 150 ft) below the city.  The route is potentially gassy, so probe drilling is mandatory throughout the project. Crews will utilize ground support including eight 3.9 m (13 ft) long rock bolts every 1.5m (5 ft) with wire mesh and channel straps as needed. The finished tunnel will be lined with a 380 mm (15 in) thick cast-in-place concrete lining.

“Big Tex will work 24 hours a day to excavate the tunnel with crews ranging in size depending on activities,” said Rachel Sackett, marketing and communications director for Southland Holdings. Based on previous work through similar geology, the project team expects TBM excavation to progress rapidly to an average of 25m (80 ft) per day, allowing the project to be completed on schedule in 2023.

---

Two Robbins Crossover TBMs to Bore Second Severomuysky Tunnel

In 1979, a 4.56 m diameter Robbins Double Shield TBM was delivered to bore the Severomuysky Service Tunnel, a 15.3 km long railway through the remote mountains of Siberia. Now, 40 years after the original machine was delivered, Robbins is returning to the role. Two 10.37 m diameter Crossover (XRE) TBMs will bore the second Severomuysky Tunnel, clocking in at 15.5 km long and running through mixed ground and fault zones. The new rail line is needed due to limitations on carrying capacity on the current Baikal-Amur Mainline (BAM) railway through the area. Currently 16 million tonnes of cargo are carried through the existing Severomuysky tunnel but the Russian Government wants to increase cargo carrying capacity by more than six times in the region.

The largest global anthracite producer, Sibanthracite Group, is taking on the tunnel construction with management by VostokCoal Management Company. The companies, owned by Dmitry Bosov, aim to increase coal transport by up to 100 million tonnes per year through the addition of the second tunnel. “Robbins has established itself on the market as the best manufacturer of hard rock machines, which are able to provide the maximum penetration rate in hard rock. This is one of the determining factors in connection with the tight deadlines for the implementation of our project. Also, Robbins is the only manufacturer to build the Crossover TBM,” said a representative of Sibanthracite Group. Other aspects of the supply include a continuous conveyor for muck removal, rolling stock, spare parts, and cutting tools.

Sibanthracite Group chose Crossover technology for a number of reasons, geology being chief among them. “A Crossover type tunnel boring machine was selected for tunneling due to the fact that the construction of the tunnel will be carried out in difficult heterogeneous geological conditions (from unstable waterlogged soils to hard rock). The Crossover is able to operate in two modes: Open mode, used while boring in hard rock formations, and closed mode (with earth pressure balance), used when boring in unstable water-logged soils,” said the Sibanthracite representative.

The lessons learned during the first Severomuysky tunnel—the importance of probe drilling, consolidation grouting, and preventing a shielded machine from becoming stuck in fault zones or squeezing ground—are all part of the Crossover TBM solution. “I was a young engineer working at Robbins when the Double Shield TBM was delivered for the first tunnel, so it is a special honor to bring this new technology to the second Severomuysky Tunnel in Siberia,” said Robbins President Lok Home. “Per the contract Robbins is supplying Crossover TBMs for the new parallel rail tunnel—these machines are made to bore in highly variable ground conditions while maintaining good advance rates. With our latest technology we hope to again prove TBMs are the better choice over Drill and Blast when difficult ground conditions are to be encountered.”

The machines will be designed for varying water pressures, ranging from 5 to 20 bar. They will feature Water Inflow Control, a system that seals off the face and periphery and creates a safe working environment in which to dewater and consolidate ground. The machines will feature probe drill ports and capabilities for 360-degree probe drilling and grouting ahead of the excavation face, while the Robbins Torque-Shift System will enable the machines to bore through collapsing ground and other situations that demand high torque. The machines will also be designed with a belt conveyor in hard rock mode that can be switched out with a screw conveyor when crossing into soft ground.

Crews will bore through the Severomuysky Ridge, a mountain range in Buryatia and part of the Stanovoy Highlands, which separates the basins of the Upper Angara and Muya Rivers. “The second Severomuysky tunnel is located in one of the most geologically active areas of our planet—on the north-eastern flank of the Baikal rift zone. The region is characterized by high seismic activity, difficult geological and hydrogeological conditions against the backdrop of a harsh climate (the summer period lasts only 80-100 days, temperatures from + 39°C in summer to -58°C in winter). The construction work on the portals is complicated by the presence of permafrost as well,” said the Sibanthracite representative. Construction of the new tunnel is expected to begin in 2020 and take five years.

---

Rescuing & Refurbishing TBMs

TBM maintenance: it’s one of the most important factors predicting project success, but it is often treated with less importance than it deserves.  Experience shows, however, that maintenance plays just as much a part in the excavation rates as the proper TBM design. Regular maintenance can keep future rebuild costs low and keep equipment efficiency high while maximizing advance rates.  Conversely, a lack of maintenance, improper operation, and/or severe ground conditions can result in undue wear and slow advance rates. In a worst-case scenario, it can even require rescuing and refurbishing of a TBM.

In this 40-minute complimentary webinar, Robbins Sales Manager Europe Detlef Jordan and iPS Tunnel Manager Barrie Willis will discuss case studies of both optimal and suboptimal maintenance and operation of TBMs.  Suboptimal examples will be discussed where TBM maintenance was insufficient and required rescuing of the machine once it became stuck or immobile.  Optimal case studies will form a guideline for recommended machine maintenance to prevent the substantial damage that can occur.  Rebuild strategies for recovered TBMs in various adverse conditions will also be discussed.

 

Watch the Recording

---

Compact TBM bores longest Rock Tunnel at 2.46 m Diameter

In August 2019, a small diameter Double Shield TBM made a big impact. The 2.46 m (8.07 ft) diameter Robbins machine completed 3,475 m (11,400 ft) of boring with no intermediate access, making it the longest rock tunnel ever bored by a Double Shield TBM under 2.5 m (8.2 ft) in diameter.

The machine completed the Parmer Lane Wastewater Interceptor in Austin, Texas, USA for contractor S.J. Louis Construction. Despite obstacles including two tight curves of 150 m (500 ft) radius and unexpected ground conditions that required modification of the cutterhead in the tunnel, advance rates were good. The machine reached up to 380 m (1,250 ft) per month while mining in single 12-hour shifts per day. “It was a hard rock TBM, and it performed better than expected through hard rock,” said Zach West, Project Manager for S.J. Louis.

The challenges for the TBM and its crew were varied, explained West. “The pairing of this tunnel length, which is on the longer side, and the diameter, which is on the smaller side, is challenging.  The survey in a small tunnel with tight radius curves and limited surface access for over two miles is very difficult.” He added that the shallow tunnel depth, and the alignment to within a few feet of sanitary lines, high-pressure gas mains, and fuel tanks for gas stations, made TBM guidance critical.  “I would say that I am most proud of our ability to guide the machine successfully through these obstacles and into our retrieval shaft within our expected tolerances.”

Through one stretch, the tunnel advanced directly between a 30 cm (12 in) diameter, high-pressure gas main and fuel tanks for a gas station with limited as-built information.  “Navigating this section took a great deal of coordination with the local utility companies.  Because the tunnel diameter was too small for an automated guidance system, we manually surveyed the front of the machine at every push to ensure the machine was on track,” said West.

“I’m proud that they mined the longest tunnel to date for a small shielded gripper machine of this size without any safety issues.  Kudos to their management philosophy and jobsite team,” said Tom Fuerst, Robbins Utility Tunneling Sales Manager. Robbins assisted the crew while in the tight 150 m (500 ft) curves and helped with modifications required to the cutterhead and disc cutter arrangement.

The tunnel is located in an environmentally sensitive aquifer, with ground conditions ranging from soft dolomite with clay to limestone from 13 to 68 MPa (2,000 to 10,000 psi) UCS.   “While we tunneled through the softer material, our best advance rate was close to 0.9 m (3 ft) per hour.  When we tunneled through the expected limestone, advance rates were over 5.2 m (17 ft) per hour.  Our best day was 25 m (81 ft) in a single shift,” said West.

The majority of the tunnel used a simple two-rock-bolt pattern for support.  In the last 10% of the tunnel, ribs and lagging were used as support. Final carrier pipe, which is now being installed, consists of 110 cm (42 in) diameter fiberglass pipe.

The successful project is part of a larger trend towards small diameter, TBM-driven rock tunnels in the United States, says Fuerst. “It is primarily due to demographics and business growth.  The parts of the USA that are growing need to build out their sewer and water infrastructure. TBMs can mine long distances with tight curves.  They can reduce the need for multiple shafts, which lowers the overall project cost.  And, given that most small diameter pipelines follow a road or municipal right-of-way, traffic problems are reduced significantly compared with open cut operations.”

The Parmer Lane Wastewater Interceptor connects to two existing lift stations at Lake Creek and Rattan Creek.  The tunnel allows for these lift stations to be decommissioned, and will provide additional flow capacity by gravity, reducing operating costs for the City of Austin.

---

Major Milestone for Delaware Aqueduct Repair as Robbins Single Shield Completes Excavation

Adapted from the official press release of the New York City Department of Environmental Protection (NYCDEP).

On Tuesday August 13, The New York City Department of Environmental Protection completed excavation of the Delaware Aqueduct Bypass Tunnel, a significant milestone in the USD $1 billion effort to repair leaks in the longest tunnel in the world. The moment happened at 6:51 a.m. when a tunnel boring machine broke through a wall of shale bedrock nearly 700 feet (210 m) beneath the Town of Wappinger in Dutchess County, New York, USA. Excavation of the tunnel was completed on budget and ahead of schedule.

“I want to congratulate the engineers, project managers and local laborers who steered us toward this milestone with considerable skill and precision,” DEP Commissioner Vincent Sapienza said. “Holing through is a major achievement for any tunneling project, especially one as large and complex as our repair of the Delaware Aqueduct. The moment is also a reminder that much work remains to be done as we move steadily toward completing this project in 2023 and ensuring the long-term reliability of the water supply system that sustains 9.6 million New Yorkers every day.”

The Delaware Aqueduct Bypass Tunnel is the largest repair project in the 177-year history of New York City’s water supply system. Its centerpiece is a 2.5-mile-long bypass tunnel that DEP is building 600 feet (180 m) under the Hudson River from Newburgh to Wappinger. When the project is finished in 2023, the bypass tunnel will be connected to structurally sound portions of the existing Delaware Aqueduct on either side of the Hudson River to convey water around a leaking section of the tunnel. The 85 mile (138 km) long Delaware Aqueduct, the longest tunnel in the world, typically conveys about half of New York City’s drinking water each day from reservoirs in the Catskills.

A massive Single Shield tunnel boring machine, manufactured by The Robbins Company in Solon, Ohio, USA, began to excavate the tunnel on Jan. 8, 2018. The tunneling machine mined 12,448 feet (3,794 m) during the 582 days that it pushed eastward from its starting point nearly 900 feet (270 m) below the surface in the Town of Newburgh in Orange County. According to data tracked by DEP, the machine excavated 89.8 linear feet (27.4 m) on its most productive day, 354.8 feet (108.1 m) during its best week, and 945 feet (288 m) during its most productive month. The tunnel boring machine excavated through three bedrock formations, starting with the Normanskill shale formation on the west side of the Hudson River, the Wappinger Group limestone formation, and finishing in the Mt. Merino shale formation on the east side of the river. The location and condition of these bedrock formations was well documented by New York City when it originally built the Delaware Aqueduct in the 1930s and 1940s. Engineers used that historical information to design the tunnel boring machine for the bypass tunnel and plan for its excavation.

As the tunnel boring machine forged ahead, it also lined the shale and limestone bedrock with precast rings of concrete. A total of 2,488 concrete rings were installed by the machine. Now that mining is finished, DEP will begin to install 16 foot (5 m) diameter steel liners inside the first layer of concrete. After the 230 steel liners are installed and welded together, they will be coated with a second layer of concrete. This “triple-pass” design will provide the bypass tunnel with structural stability and prevent leaks from occurring again in the future. During the excavation, the tunnel boring machine was driven, maintained and supported by dozens of local laborers who worked 24-hours, six days a week. They operated cranes, trucks and underground trains to collect the pulverized rock and haul it to the surface. They removed and replaced cutting discs on the front of the machine, and maintained the many complex systems that kept the tunnel boring machine functioning properly.

The Delaware Aqueduct Bypass Tunnel is the first tunnel built under the Hudson River since 1957, when the south tube of the Lincoln Tunnel was finished.

Background on the Delaware Aqueduct repair project

DEP has monitored two leaking sections of the Delaware Aqueduct – one in Newburgh, and the other in the Ulster County town of Wawarsing – since the early 1990s. The leaks release an estimated 20 million gallons (76 million liters) per day, about 95 percent of that escaping the tunnel through the leak near the Hudson River in Newburgh. DEP has continuously tested and monitored the leaks since 1992. The size of the cracks in the aqueduct and the rate of leakage have remained constant over that time.

In 2010, the City announced a plan to repair the aqueduct by building a bypass tunnel around the leaking section in Newburgh, and also by grouting closed the smaller leaks in Wawarsing. The project began in 2013 with the excavation of two vertical shafts in Newburgh and Wappinger to gain access to the subsurface. These shafts, 845 and 675 feet (258 and 206 m) deep respectively, were completed in 2017. Workers then built a large underground chamber at the bottom of the Newburgh shaft. That chamber has served as the staging area for assembly and operation of the tunnel boring machine, and as the location from which excavated rock is brought to the surface by underground trains and a large crane.

The existing Delaware Aqueduct will stay in service while the bypass tunnel is under construction. Once the bypass tunnel is nearly complete and water supply augmentation and conservation measures are in place, the existing tunnel will be taken out of service and excavation will begin to connect the bypass tunnel to structurally sound portions of the existing aqueduct. While the Delaware Aqueduct is shut down, work crews will also enter the aqueduct in Wawarsing to seal the small leaks there, roughly 35 miles (56 km) northwest of the bypass tunnel.

The project will mark the first time that the Delaware Aqueduct will be drained since 1958. In 2013, DEP installed new pumps inside a shaft at the lowest point of the Delaware Aqueduct to dewater the existing tunnel before it is connected to the new bypass tunnel. Those pumps will be tested several times before the tunnel is drained in 2022. The nine pumps are capable of removing a maximum of 80 million gallons (302 million liters) of water a day from the tunnel—more than quadruple the capacity of the pumps they replaced from the 1940s. The largest of the pumps are three vertical turbine pumps that each measure 23 feet (7 m) tall and weigh 9 US tons (8 metric tons).

Background on the tunnel boring machine “Nora”

The Delaware Aqueduct Bypass Tunnel was excavated by one of the world’s most advanced tunnel boring machines (TBM). The Robbins Single Shield TBM – which measures more than 470 feet (140 m) long and weighs upwards of 2.7 million pounds (1.2 million kg) – was named in honor of Nora Stanton Blatch Deforest Barney, a noted suffragist and the first woman in the United States to earn a college degree in civil engineering. Nora, who worked for the City’s as a draftsperson during the construction of Ashokan Reservoir, was also the first female member of the American Society of Civil Engineers.

The USD $30 million TBM arrived at the site in Newburgh in 2017. It was delivered in 22 pieces and took four months to assemble. The 21.6-foot (6.58 m) diameter TBM was built to withstand more than 30 bar of pressure. The machine needed to withstand high pressure because workers encountered huge inflows of water under immense pressure when the aqueduct was first built more than 70 years ago. The TBM was equipped with pumping equipment to remove up to 2,500 gallons (9,400 liters) of water per minute away from the tunnel as the machine pushed forward. The TBM was also outfitted with equipment to install and grout the concrete lining of the tunnel, and to convey pulverized rock to a system of railroad cars that followed the TBM as it worked. The railroad cars regularly traveled back and forth between the TBM and the bottom of Shaft 5B in Newburgh, delivering workers, equipment and rock between the two locations.

 

---

Rebuilding TBMs: Are Used TBMs as Good as New?

Much has been made worldwide of the difference in performance between new and rebuilt TBMs. Worldwide, a bias exists that seems to favor new machines, but is the bias warranted? The reuse of machines can, if done to exacting standards, reduce costs and time to delivery while also reducing the carbon footprint. But guaranteeing the quality of TBM rebuilds is another issue—one that seems only minimally improved by the existence of international guidelines. This paper discusses the process of machine rebuilds and the use of rebuilt TBMs with performance examples from projects worldwide. It seeks to establish guidelines and recommendations based on real experiences of success in the shop and in the field.

---

Breaking Through Tough Ground in the Himalayas: Nepal's First TBM

Years of hard work and planning have paid off at the Bheri Babai Diversion Multipurpose Project. This 12 km tunnel is not only breaking through a historically difficult mountain range, but it has also managed to break down the notion, to the people of Nepal, that drill and blast is this only way to excavate the extreme conditions in the Himalayas. This paper highlights the first TBM in Nepal and how it is managing to bore at an exceptional advance rate of over 700 m per month, with a high of 1202 m in one month. It examines which design features of the Double Shield TBM are contributing to the great excavation rates, and how the crew’s operational methods have maximized these results.

---

Tunneling in Mixed Face Conditions: An Enduring Challenge for EPB TBM Excavation

EPB TBM tunneling in mixed face conditions—partially in both rock and soil—is inherently problematic for even the most experienced crews. Over-excavation, excessive damage to cutter tools and regular cutterhead interventions are major challenges when negotiating mixed face geology. This paper draws from real field experiences, including successful bores in abrasive rock and soil at India’s Chennai and Bangalore metro projects, to determine the optimal operational parameters for TBMs in such conditions. It also addresses reduction of air losses to facilitate cutterhead interventions under hyperbaric conditions when installation of safe-haven grout blocks is not an option due to surface structures.

---

7.93 m Open TBM Shotcrete System Improvement and Innovation - Jilin Project, China

In May 2018, a 7.93 m diameter open gripper (Main Beam) TBM completed the 24.3 km long Jilin Lot 3 tunnel under a maximum overburden of 272.9 m. The tunneling operation for the water transfer project, located in northeastern China, achieved a national record of 1,423.5 m in one month despite challenging conditions. This paper presents an improved, innovative shotcrete system for TBM preliminary lining, developed through experience on previous projects. The shotcrete system, along with other structural design elements and a properly developed ground support program, allowed the TBM to bore successfully in variable hard rock and fault zones. The paper discusses how the shotcrete system and structural design increased safety and improved performance in a cost-effective manner. It defines the variables that allowed the TBM to advance at rapid rates and makes recommendations for future types of projects that could benefit from the shotcrete system.

---